Al Qaeda Leader’s Edict To Yemen Affiliate Is Said To Prompt Alert

WASHINGTON — The Obama administration’s decision last week to close nearly two dozen diplomatic missions and issue a worldwide travel alert resulted from intercepted electronic communications in which the head of Al Qaeda in Pakistan ordered the leader of its affiliate in Yemen, the terrorist organization’s most lethal branch, to carry out an attack as early as this past Sunday, according to American officials.

The intercepted conversations last week between Ayman al-Zawahri, who succeeded Osama bin Laden as the head of the global terrorist group, and Nasser al-Wuhayshi, the head of the Yemen-based Al Qaeda in the Arabian Peninsula, revealed one of the most serious plots against American and other Western interests since the attacks on Sept. 11, 2001, American intelligence officials and lawmakers have said.

It is highly unusual for senior Qaeda leaders in Pakistan to discuss operational matters with the group’s affiliates, so when the intercepts between the two senior Qaeda leaders were collected and analyzed last week, senior officials at the C.I.A., the State Department and the White House immediately seized on their significance. Members of Congress were quickly provided classified briefings on the matter, American officials said.

“This was significant because it was the big guys talking, and talking about very specific timing for an attack or attacks,” said one American official who had been briefed on the intelligence reports in recent days.